Description
Description: Endomorphins are recently discovered endogenous opioid peptides composed of four amino acids: Endomorphin-1 (EM-1) is Tyr-Pro-Trp-Phe-NH2, and Endomorphin-2 (EM-2) is Tyr-Pro-Phe-Phe-NH2. These peptides have a very high affinity and specificity for mu-opioid receptors as it has been reported in many pharmacological studies. EM-1 is distributed in many brain regions, whereas EM-2 is prevalent in brainstem and spinal cord. EM-1 and EM-2 exert their antinociceptive activity by interacting with mu-opioid receptors. EM-1 anf EM-2 bind with mu-opioid receptor with high affinity and selectivity in comparison with binding to opioid delta and kappa receptors. EM-1 and EM-2 tetrapeptides activate G-proteins and inhibit adenylyl cyclase activity when bind to mu-opioid receptors